Merge pull request #249 from bheuer/master

finished work on startscreen
change to native Dialogs if possible
Merge pull request #1 from ilastik/master

Pull changes
added import statement for PathComponents (#252)
Merge pull request #253 from burgerdev/master

Fix for bug #252
enabled tracking workflow autodiscovery; improved ImportError handling in workflows init
more protection against missing tracking dependency
incorporate 5d threshold operator into synapseObjectWorkflow
add a colortable to output layer
returned small filtered components as colored
make objects layer visible by default
shell: Removed "Play Recording" menu item.  Must use command-line to play recordings.
object feature selection.

* new feature selection dialog.

* features implemented in plugins.

* new dependency, yapsy, for plugin management.
Fix issue #227
clean up carving applet
work on path input of ilastik.py
save selected object features
Changed order in which applets are created and connected in IlastikShell in order to fix Issue #229. It should be fixed now.
remove brush size names, #256.

Still todo: adjust "Size:" string in GUI to read "Brush size:"
use new signature of notify_failed